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The triple response phenotype is characteristic for seedlings treated with the phytohormone ethylene or its direct precursor 1-aminocyclopropane-carboxylic acid, and is often employed to find novel chemical tools to probe ethylene responses. We identified a benzoxazole-urea derivative (B2) partially mimicking ethylene effects in a triple response bioassay. A phenotypic analysis demonstrated that B2 and its closest analogue arinole (ARI) induced phenotypic responses reminiscent of seedlings with elevated levels of auxin, including impaired hook development and inhibition of seedling growth. Specifically, ARI reduced longitudinal cell elongation in roots, while promoting cell division. In contrast to other natural or synthetic auxins, ARI mostly acts as an inducer of adventitious root development, with only limited effects on lateral root development. Quantification of free auxins and auxin biosynthetic precursors as well as auxin-related gene expression demonstrated that ARI boosts global auxin levels. In addition, analyses of auxin reporter lines and mutants, together with pharmacological assays with auxin-related inhibitors, confirmed that ARI effects are facilitated by TRYPTOPHAN AMINOTRANSFERASE1 (TAA1)-mediated auxin synthesis. ARI treatment in an array of species, including Arabidopsis, pea, tomato, poplar, and lavender, resulted in adventitious root formation, which is a desirable trait in both agriculture and horticulture. [ABSTRACT FROM AUTHOR]

Lavender (Lavandula angustifolia Mill.) is a valuable crop with diverse applications, but its in vitro rooting can be hindered by its sensitivity to natural auxins and it often fails to root due to callus formation. The current study investigates the effects of light spectra emitted by LEDs and the application of trans-cinnamic acid (t-CA) on the morphology, propagation, and rooting of lavender shoots in vitro. Initially, the influence of different concentrations of t-CA (0, 1.25, 2.5, or 5 µM) was evaluated under fluorescent light. The application of 1.25 µM t-CA was found to be the most effective in promoting root development while minimizing callus formation. Subsequently, the impact of different light spectra (fluorescent light and combinations of blue, red, and far-red monochromatic LED light) was explored. The combination of red and far-red (RFR) light significantly accelerated rooting and resulted in the most substantial increase in root number and length. Finally, the combined effects of 1.25 µM t-CA and RFR light were assessed. This combination produced the most favorable overall results, notably, a 4.3-fold increase in lateral root number compared to RFR light alone. These findings underscore the potential of optimizing both t-CA concentration and light spectra to enhance the in vitro propagation of lavender. [ABSTRACT FROM AUTHOR]

Fluorinated cytokinins have emerged as promising alternatives to traditional cytokinins in Phalaenopsis plant tissue culture, offering enhanced stability and bioactivity. However, their metabolic fate and impact on endogenous cytokinin profiles remain largely unexplored. This study builds upon previous research to investigate the comparative metabolism of the traditional cytokinin 6-Benzylaminopurine (BA) with the successful alternatives 6-(3-fluorobenzylamino)purine (FmT) and 6-(3-fluorobenzylamino)purine 9-riboside (FmTR). Additionally, this study examines the impact of another crucial factor, the use of ventilated versus closed containers, on metabolic processes. The results revealed the distinct metabolic profiles associated with each treatment, highlighting the complex interplay between exogenous and endogenous cytokinin levels. This study is the first to investigate the effects of these stable, synthetic, and exogenous cytokinins on the naturally occurring cytokinin levels and their metabolites in micropropagated Phalaenopsis. Additionally, we proposed an alternative inactivation pathway involving the conversion of FmTR and BA to pT and pTR. These findings provide valuable insights into the intricate relationship between cytokinin metabolism and plant growth under in vitro conditions. [ABSTRACT FROM AUTHOR]

Hardy geranium is a popular ornamental plant with a high market demand. As a result, there is a strong need for continuous innovation to improve its ornamental qualities. Interspecific hybridization is a widely used technique for introducing desirable traits and creating new cultivars with added value. To explore the possibilities of creating novelty within the Geranium genus, we conducted 2438 interspecific crosses over three flowering seasons, resulting in the successful harvest of 445 seeds and the final production of 82 seedlings. Using embryo rescue increased the germination rate of a seedling from 0.17% to 1.01%. To validate the paternal genetic contribution in the new seedlings, we used amplified fragment length polymorphism (AFLP) to assess the proportion of uniquely inherited paternal markers in all seedlings. AFLP analysis confirmed that 54 of the 82 seedlings were indeed true hybrids (65.8% hybridization success rate). A morphological evaluation of the flowers and leaves, including flower diameter (mm), style length (mm), number of flowers, flowering period (weeks), and color of both flowers and leaves, provided further confirmation of the F1 hybrid status of the seedlings. The results of our interspecific breeding demonstrated the efficiency of interspecific hybridization in hardy geraniums and its potential to create distinctive and novel cultivars for the ornamental market. [ABSTRACT FROM AUTHOR]

Topolin cytokinins have emerged as valuable tools in micropropagation. This study investigates the metabolism of meta-topolin riboside (mTR) in three distinct tree species: Handroanthus guayacan and Tabebuia rosea (Bignoniaceae), and Tectona grandis (Lamiaceae). Employing labeled N15 mTR, we unraveled the complex mechanisms underlying cytokinin homeostasis, identifying N9-glucosylation as the principal deactivation pathway. Our findings demonstrate a capacity in T. rosea and H. guayacan to reposition the hydroxyl group on the cytokinin molecule, a previously unexplored metabolic pathway. Notably, this study reveals remarkable interfamilial and interspecies differences in mTR metabolism, challenging established perspectives on the role of callus tissue in cytokinin storage. These insights not only illuminate the metabolic intricacies of mTR, a cytokinin with interesting applications in plant tissue culture, but also enhances our understanding of cytokinin dynamics in plant systems, thereby enriching the scientific discourse on plant physiology and cytokinin biology. [ABSTRACT FROM AUTHOR]

To date, in vitro somatic embryogenesis is the only option for the mass vegetative propagation of cocoa. The somatic embryogenesis of Indonesian cocoa clones SUL1 and SUL2 was investigated, focusing on primary and cyclic secondary embryogenesis. The study showed that staminode explants were more effective than petal explants in generating primary somatic embryos (SEs), especially when cultured in liquid medium containing 2 mg/L 2,4-D and 0.25 mg/L kinetin, with the staminodes of SUL2 producing a significant number of globular SEs. In contrast, SUL1 showed limited SE production. The study also demonstrated that fragmenting cotyledons and hypocotyls of the SEs of SUL2 and culturing them on an induction medium supplemented with 2,4,5-T and proline resulted in a high yield of secondary SEs. This cyclic embryogenesis process, in which the SEs remained attached to the maternal tissue, facilitated continuous SE production and development. The addition of proline was found to improve the quality of SEs, leading to higher production of well-organized, milky SEs with a better-defined meristematic structure. These results suggest a promising protocol to produce SEs from cocoa, with implications for plant transformation and gene editing applications. [ABSTRACT FROM AUTHOR]

Potato propagation through tubers and seed is an inefficient way of propagation thus we propose an alternative method in this study which is in vitro propagation. Plantlets were raised from True Potato Seeds (TPS) in test tubes containing 10 mL of Murashige Skoog (MS) medium. Subculturing was done after every 21 days and after four subsequent subculturing, when there was an adequate quantity of stock material, uninodal cuttings of about 3–4 mm in length were prepared from in vitro proliferated potato plants by excising leaves of 1–2 mm on each side of the node. Prepared uninodal cuttings were cultured on ½ strength MS medium for root primordia development. The selected uninodal cuttings with root primordia were encapsulated with sodium alginate solution (3.5% (w/v), mixed with 1.25% charcoal and different concentration of fungicide (thiophanate methyl, sigma) to enhance the viability percentage of synthetic seed. Furthermore, these encapsulated uninodal cuttings were subjected to different storage intervals to check maximum storage. Results showed that optimum dose for fungicide is 150 mg/L as it resulted in good viability percentage, shoot number, shoot length, rooting percentage, root number, root length and ideal for bead formation with sodium alginate. Similarly, results revealed that encapsulated uninodal cuttings can be stored at a temperature of 4°C up to 45 days with a survival rate of 63.33%. Encapsulated uninodal cutting stored for 60 days showed a poor viability percentage of about 43.03%. It can be concluded that optimum dose of 150 mg/L with storage time of 45 days should be used to get a better outcome for synthetic potato seed production. [ABSTRACT FROM AUTHOR]